Such connector brackets and plug-in coupling systems are used on semitrailer trucks, after a mechanical coupling of the semitrailer, to also connect the supply lines of the tractor vehicle to the semitrailer in largely automated fashion, so that the driver no longer has to climb between the tractor and the semitrailer and plug in the connection lines there, such as for the compressed air and electricity supply, by hand.
One prior art of this kind is disclosed by DE 10 2004 024 333 A1 with a plug-in coupling system, in which a plug-in device on the semitrailer with a connector arranged stationary therein is introduced into a socket arranged underneath the insertion opening. Thus occurs while a king pin situated on the underside of the semitrailer bottom is driven into the fifth wheel. For this, the plug-in device has a wedge shape, matched to the geometry of the insertion opening, so that it is secured with form fitting by the insertion opening. When the semitrailer truck is driving on a curve, the plug-in device swivels in fixed position within the insertion opening, thanks to its being mounted so as to rotate about the king pin. The major drawback of this known system is that the connector at the semitrailer is open in the driving direction and subjected to considerable dirt and grime during the drive. This problem is further aggravated when semitrailers outfitted with the known plug-in device are used in a mixed fleet whose tractor vehicles are outfitted with a socket not yet designed complementary to the connector, for then solids swirled up by the tractor can get into the connector pointing opposite the driving direction. In the winter months, the plug-in device can also become disabled by ice build-up.